BOSTON, Massachusetts (CNN) -- For a self-described "skinny guy from the Southside with a funny name," it's been quite a ride.

Barack Obama, the son of a Kenyan father and a white mother from Kansas, born and raised in Hawaii, was a little-known Illinois state senator as recently as late last year.

Now, he's the state's Democratic U.S. Senate candidate, the subject of major features in The New Yorker and The New Republic magazines, the odds-on favorite to win the seat being vacated by Republican Peter Fitzgerald -- and he's getting the Democratic convention's glamour slot, giving the keynote address in the heart of prime time. (Obama's speech)

And yet, in the middle of reporters' scrums and enthusiastic greetings from strangers, Obama has remained preternaturally calm.

Is he worried about the keynote? "There's going to be some adrenaline," he told a reporter the morning of his big night. "But the pressure I'm experiencing is nothing compared to folks I'm meeting getting laid off. ... That's real pressure."

And how about the Senate? Isn't he a shoo-in?

"Three months is a lifetime in politics," Obama said after giving a speech at an environmental rally in Boston's North End. (Interactive: Democratic players)

'He's parking the car'

He should know. Chicago Tribune reporter Dave Mendell remembered covering Obama last November, when he was just part of the pack of seven candidates in a Democratic Senate primary expected to be won by either millionaire Blair Hull or state comptroller Dan Hynes. Obama wasn't just a guy in a car making speeches to chambers of commerce and Rotary clubs -- he was the driver as well.

And then Obama caught a break. Divorce records revealed ugly details about Hull's marriage, and voters started gravitating to Obama.

"The rich guy flamed out, and Obama was right there," said Mendell. "He ran a really smart primary campaign. He waited until the ninth inning to score all his runs. ... It was masterfully done."

With the Illinois Republican Party struggling to come up with a candidate after its primary winner, Jack Ryan, dropped out of the race, Obama now faces scant opposition.

Ryan withdrew in June after court documents were unsealed in which his ex-wife alleged that he asked her to engage in sexual activity in front of patrons at sex clubs. Ryan denied the allegations. (Full story)

But Obama was a favorite even before Ryan left the race.

A Chicago Tribune/WGN-TV poll showed Obama with a large lead. The poll in late May showed Obama leading Ryan 52 percent to 30 percent. The poll had a margin of error of plus or minus 4 percentage points.

And a survey of 600 voters showed only 29 percent had a favorable opinion of Ryan, while 46 percent had a favorable opinion of Obama, the Tribune reported.

A jog, a shower, a nap -- the spotlight

The Democratic keynote address is a plum usually offered rising stars, such as then-Indiana Gov. Evan Bayh (1996) and then-Texas state Treasurer Ann Richards (1988).

But, as CNN analyst Bill Schneider noted, it's usually a little-remembered speech, with only Mario Cuomo's 1984 stemwinder and Richards' 1988 "Where was George?" litany resonating from the past generation, he said.

Speaking in his van on the way back to the FleetCenter after the environmental speech, Obama said he was going to stick close to home in his remarks to the convention.

"If I just focus on the stories I'm hearing from people back home in Illinois," he said, he'll get his point across. It's a message of common sense, he added, not the "slash and burn politics" so prominent in today's discourse.

"People know [President] Bush isn't the cause of every problem in the world, and they know the Democrats aren't a bunch of raving lunatics," he said.

"What people want to know is who has a set of concrete plans to help them send their kids to college, or save for retirement." And that's what the Democrats can offer, he said.

Obama, who turns 43 in August, planned on taking a short break before the keynote. He was set to do interviews until 4 p.m., and "then I'm going to get a jog in. Then a long shower, and maybe a nap." The speech is done, he added; it was written a couple weeks ago.

But, in the meantime, there's the whirlwind. As Obama munches on a sandwich in the van, joking with passengers one minute and offering thoughtful responses the next, he notes the toll the campaign has taken on his already-wiry body.

"I've lost eight pounds since the campaign started," he said.

But he doesn't sound perturbed. After all, a campaign is a marathon, and even a keynote address is just one night.